A roll former for steel plate (3) which enables edge corner deformation of steel plate edges (4) to be avoided, that is, a roll former for steel plate comprised of a top roll (1) and a bottom roll (2), the roll former for steel plate characterized by forming convex curved parts (5) having a bending direction opposite to a bending direction of the steel plate (3) in regions of the bottom roll (2), which forms the outer side of the steel plate (3), which contact the steel plate edges (4).